Although many privacy advocates are likely to be up in arms about the potential development, Apple plans to use the feature to make its devices more secure.

Currently, the Cupertino-based firm provides its own “Find My iPhone” service, which enables users to track their handset when it has been lost or stolen. As it stands, however, phones cannot be traced when turned off.

The recently granted patent indicates that in the future, users may be asked to enter a passcode before they turn their phone off, and if the incorrect code is entered the device will enter a traceable sleep mode.

The feature may prove a useful addition in the fight against mobile phone theft. Already, tracking features and other security protocols have reduced smartphone theft by 50 per cent, according to the Independent.

The patent also outlines plans for iPhone owners to operate their device’s camera remotely while in sleep mode, enabling them to potentially take a photograph of the individual who has stolen their phone.

The document indicates that the iPhone will “periodically exit an unpowered state and transmits location data” automatically. It is likely that Apple will need to be wholly transparent with users as to how this feature would be implemented, in order to avoid accusations of surveillance.

In any case, the sheer number of patents issued to technology giants like Apple means that the iPhone tracking feature may never see the light of day. Earlier this month, it was reported that Google had been granted a patent for a wearable deodoriser, which was capable of telling users how nearby their friends were so they could avoid them if necessary.